1. Field of the Invention
The present invention relates to plasma chemistry, and more particularly to devices and methods for transporting and motivating ionized gases which allow a separation of plasma generation and plasma application.
2. Description of Related Art
Plasmas of ionized gases are routinely used in electronics and semiconductor manufacturing. Such plasmas are an almost neutral mix of electrons and ions that will recombine as they cool off. The challenge in many applications is to use the plasmas to do useful work before they cool off. One way to do that is to generate the plasma itself at or near the point of use. But that situation often results in compromises being made between what is best for generating the plasma in the first place and what is best for working the plasma once generated.
It occurs from this that it would be advantageous to generate the plasmas in one area specialized to plasma-generation, and then to move it to an area where it can do its work. But long transportation paths can result in a loss of momentum and a cooling down of the plasma. There is also the problem of how best to pump the plasma from place to place.
Ion-propulsion engines are one form of device that can pump or move plasmas. But conventional ion-propulsion engines are not highly developed yet and their operation is non-ideal. Plasma vacuum pumps have also been developed that use arrays of permanent magnets and electrically biased electrodes. Such plasma vacuum pumps try to force large amounts of plasma and effluent gas into high pressure chambers at super-thermal speed through ducts. Sustaining higher compression ratios seems to require relatively long ducts. But only limited success has been achieved with short ducts. Long ducts suffer too much electron cooling through collisions with neutral gas molecules. The electrically biased electrodes are susceptible to sputtering when exposed to the plasma.